Quality assessment according to the Newcastle-Ottawa scale
| Author . | Year . | Selection . | Comparability . | Outcome . | Exposure . | Total . |
|---|---|---|---|---|---|---|
| Cohort studies | ||||||
| Blomberg14 | 1993 | 4 | 1 | 2 | — | 7 |
| Memon18 | 1994 | 4 | 0 | 2 | — | 6 |
| Cerhan15 | 2001 | 4 | 2 | 2 | — | 8 |
| Hjalgrim17 | 2007 | 4 | 2 | 3 | — | 9 |
| Erber16 | 2009 | 4 | 2 | 3 | — | 9 |
| Average | 4 | 1.4 | 2.4 | — | 7.8 | |
| Case-control studies | ||||||
| Brandt6 | 1996 | 3 | 2 | — | 2 | 7 |
| Adami5 | 1997 | 4 | 2 | — | 3 | 9 |
| Nelson10 | 1998 | 4 | 2 | — | 2 | 8 |
| Maguire-Boston9 | 1999 | 3 | 2 | — | 3 | 8 |
| Tavani11 | 1999 | 3 | 2 | — | 2 | 7 |
| Chow8 | 2002 | 4 | 2 | — | 2 | 8 |
| Zhu13 | 2003 | 3 | 2 | — | 2 | 7 |
| Zhang12 | 2004 | 4 | 2 | — | 2 | 8 |
| Cerhan7 | 2008 | 3 | 2 | — | 3 | 8 |
| Average | 3.4 | 2 | — | 2.3 | 7.7 |
| Author . | Year . | Selection . | Comparability . | Outcome . | Exposure . | Total . |
|---|---|---|---|---|---|---|
| Cohort studies | ||||||
| Blomberg14 | 1993 | 4 | 1 | 2 | — | 7 |
| Memon18 | 1994 | 4 | 0 | 2 | — | 6 |
| Cerhan15 | 2001 | 4 | 2 | 2 | — | 8 |
| Hjalgrim17 | 2007 | 4 | 2 | 3 | — | 9 |
| Erber16 | 2009 | 4 | 2 | 3 | — | 9 |
| Average | 4 | 1.4 | 2.4 | — | 7.8 | |
| Case-control studies | ||||||
| Brandt6 | 1996 | 3 | 2 | — | 2 | 7 |
| Adami5 | 1997 | 4 | 2 | — | 3 | 9 |
| Nelson10 | 1998 | 4 | 2 | — | 2 | 8 |
| Maguire-Boston9 | 1999 | 3 | 2 | — | 3 | 8 |
| Tavani11 | 1999 | 3 | 2 | — | 2 | 7 |
| Chow8 | 2002 | 4 | 2 | — | 2 | 8 |
| Zhu13 | 2003 | 3 | 2 | — | 2 | 7 |
| Zhang12 | 2004 | 4 | 2 | — | 2 | 8 |
| Cerhan7 | 2008 | 3 | 2 | — | 3 | 8 |
| Average | 3.4 | 2 | — | 2.3 | 7.7 |